CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

[0001] This patent application claims the benefit of U.S. Provisional Patent Application No. 62/845,904, filed May 10, 2019, the entire teachings and disclosure of which are incorporated herein by reference thereto.

FIELD OF THE INVENTION

[0002] The present invention relates to a multilayered filter media that is used to minimize flow restriction while maintaining desired efficiency, particularly for animal confinement filtration applications, but that also may be used for other such filtration applications.

BACKGROUND OF THE INVENTION

[0003] Various patent publications propose use of polymeric nanofiber or microfibers in filter media constructions such as disclosed in U.S. Patent Nos. 8,512,431; 5,672,399; 4,650,506 and US Patent Publication No. 2011/0114554 to Li et. al. and US Patent Publication No. 2011/0210081 to Green et. al. The issue with such nanofibers is that such nanofibers are rather delicate and subject to processing issues such as discussed in the‘506 patent to Barris et al. The‘554 publication to Li et al. proposes use of electrospun fine fibers and a multi-component (i.e. bicomponent) substrate filter media comprising a high melt polymeric component and a low melt polymeric component, in which the low melt polymeric component acts a bonding agent. The‘081 publication to Green et al. also proposes bonding alternating layers of bicomponent scrim layers and fine fiber layers that may be enhanced via thermal bonding. However, the‘081 publication to Green et al. is directed toward liquid filtration applications that are subjected to momentum and viscosity posed by liquid, and such a construction would appear restrictive with so many layers.

[0004] In a different filter application, U.S. Patent No. 9,510,557 to Ball et al. discloses an air filter for an animal confinement application such as for filtering out the porcine reproductive and respiratory syndrome virus (PRRSV). The filter may be a deep pleated filter of synthetic filter media with at least a MERV 14 rating and efficiency sufficient to filter out the PRRSV in high air flow applications. The media is highly processed with embossments formed into the media to provide spacers to provide for structural support and open filter structure for airflow. Adhesive bead spacers are also applied. For example, filter media embossing methods disclosed include those described in U.S. Pat. No.

6,685,833. U.S. Pat. No. 5,290,447, U.S. Pat. No. 5,804,014, and DE 19755466 Al. The ‘557 patent to Ball discloses use of hydrophobic electret filter media; and also discloses that a composite filter media may be preferred in some embodiments. While nanofibers are mentioned as a possibility in the‘557 patent to Ball, the specific example for animal confinement filtration discusses a meltblown polypropylene that is plasma fluorinated and laminated to a polyester substrate.

BRIEF SUMMARY OF THE INVENTION

[0005] The inventors have realized that the delicacy of fine nanofibers are not readily reconcilable with aggressive filter media processing such as embossing, and that aggressive filter media processing may damage integrity of conventional nanofiber medias and/or may otherwise not provide suitable filtration characteristics. Accordingly, new filters medias and methods are disclosed herein that may be used with embossing or other processing, and/or may otherwise used in filter media arrangements.

[0006] One aspect is directed toward a multi-layered filter media, comprising: (a) first and second bicomponent support layers, each bicomponent support layer including a plurality of fibers and including a high melt component and a low melt component with the high melt component having a higher melting point than the low melt component; and (b) first and second nanofiber layers sandwiched between the first and second bicomponent support layers, with the first nanofiber layer deposited upon the first bicomponent support layer, and the second nanofiber layer deposited upon the second bicomponent support layer. The first and the second nanofiber layers are bonded to the first and second bicomponent support layers via the low melt component. Further, the low melt component bonds the first and second bicomponent support layers together. [0007] Another aspect is directed toward a multi-layered filter comprising: i. at least two adjacent layers of nanofiber filtration media made by force-spinning or centrifugal spinning; and ii. upstream and downstream support layers adjacent respective upstream and downstream nanofiber filtration media layers. The adjacent layers are thermally bonded together.

[0008] Yet another aspect is directed toward implementation of a created multi-layered filter media in a filter media pack that has embossments. The multi-layered filter media comprises: (a) first and second bicomponent support layers, with each bicomponent support layer including a plurality of fibers including a high melt component and a low melt component, with the high melt component having a higher melting point than the low melt component; and (b) nanofibers interposed between the first and second bicomponent support layers and bonded thereto via the low melt component. The low melt component also bonds the first and second bicomponent support layers together. This multi-layered filter media is also embossed with a plurality of embossments and is configured into a media assembly having an inlet face and an outlet face. This configuration provides the filter media pack with a plurality of sections of the multi-layered filter media extending between the inlet face and the outlet face in a spaced relationship to define air flow channels between the sections of the multi-layered filter media, with the embossments providing at least one of spacing and rigidity of the sections to maintain the spaced relationship.

[0009] Various features or other aspects recited below may be provided in combination with any of the aspects above (and/or also in combination with one or more other features recited below), and/or may separately provide other inventive aspects. Preferably, the above aspects include one or more of the following features below.

[0010] The first nanofiber layer may be deposited upon the first bicomponent support layer to provide a first filter media composite, with the second nanofiber layer deposited upon the second bicomponent support layer to provide a second filter media composite.

[0011] Preferably, the first filter media composite and the second filter media composite are of a same construction to provide a symmetrical structure through a media thickness over a central extension of the multi-layered filter media. [0012] The nanofiber layers may be nanofiber filtration media layers which are identical.

[0013] In the multi-layered filter media the various layers may be embossed and pleated together.

[0014] The first and second bicomponent support layers may be provided by scrims, each scrim having a basis weight of between 10 gsm and 200 gsm and an average fiber size of between 2 micron and 30 micron and a caliper thickness of between 0.03 millimeter and 0.75 millimeter; and wherein each layer of the first and second nanofiber layers comprises a basis weight of between 0.005 gsm and 1.5 gsm and an average fiber size of no greater than 250 nanometer.

[0015] The support layers may be spunbond support layers.

[0016] The first and second nanofiber layers (or nanofibers) may comprise nanofibers comprising at least one polymer type selected from the group consisting of: a polyamide, a polyvinybdene fluoride, a polytetrafluoroethylene, a polyurethane, a cellulose acetate, a polycarbonate, and a polystyrene.

[0017] The bi-component support fibers may comprise at least one the following configurations: a core/sheath, a side-by-side, a segmented, an islands-in-the-sea.

[0018] The bi-component support fibers fibers may comprise at least one polymer type selected from the group consisting of: a polyester, a PEN polyester, a PCT polyester, a PBT polyester, a soluble co-polyester, a polyamide, a polystyrene, a co-polyamide, a polylactic acid, an acetal, a polyurethane, a polystyrene, a high-density polyethylene, and a linear low density polyethylene.

[0019] The multi-layered filter media can have high efficiency and low pressure drop, and for example may comprise a pressure drop less than 0.4 inch of water at 1968 cfin air flow measured according to ASHRAE 52.2, and an isopropyl alcohol discharged efficiency MERY rating of at least 14 measured according to ASHRAE 52.2. [0020] The first and the second nanofiber layers are preferably thermally laminated to the first and second bicomponent support layers.

[0021] The first and second bicomponent support layers are preferably thermally laminated together.

[0022] The multi-layered filter media may be pleated to define a plurality of pleats, with the pleats including pleat tips at an inlet face and pleat tips at an outlet face. The pleats typically include a plurality of adjacent pleat panels providing inlet pleat channels opening toward the inlet face and outlet pleat channels opening toward the outlet face.

[0023] Such pleated media preferably further comprises a plurality of embossments formed into the multi-layered filter media and projecting into the inlet pleat channels and into the outlet pleat channels.

[0024] Preferably adhesive beads are applied proximate pleat tips and at least partially over at least some of the embossments proximate at least one of the inlet face and the outlet face to maintain a spacing of the pleats.

[0025] Preferably nanofibers are provided by first and second nanofiber layers deposited upon the first and second bicomponent support layers, respectively.

[0026] Such first and the second nanofiber layers preferably are thermally laminated to the first and second bicomponent support layers, and the first and second bicomponent support layers are thermally laminated together. For example, the first nanofiber layer can be deposited upon the first bicomponent support layer to provide a first filter media composite, and the second nanofiber layer can be deposited upon the second bicomponent support layer to provide a second filter media composite.

[0027] Preferably such first filter media composite and such second filter media composite are of a same construction to provide a symmetrical structure through a media thickness over a central extension of the multi-layered filter media. [0028] In many of the useful configurations, the media assembly may be in the form of a pleated filter pack comprising pleats with pleat panel panels providing the sections of the multi-layered filter media. The pleats provide pleat tips at the inlet face and pleat tips at the outlet face, with a pleat depth between the inlet face and the outlet face of between 1 and 42 centimeters; with a pleat spacing measured between pleat tips at the inlet face or the outlet face that is between 0.5 and 30 millimeters. The embossments have maximum formed depth of between 0.2 and 12 millimeters.

[0029] According to pleated configurations, adhesive beads may be applied proximate pleat tips and at least partially over at least some of the embossments proximate at least one of the inlet face and the outlet face to maintain spacing and rigidity of the pleated filter pack.

[0030] An aspect may also be directed toward a deep pleat filter comprising multilayered filter media, comprising: a rectangular border frame having four sides; a pleat pack formed from a rectangular pleated filter element of the multi-layered filter media, with the multi-layered filter media being pleated to provide a plurality of pleat tips. By deep pleat it is meant that each pleat has a depth of greater than 6 centimeters to provide depth (more typically greater than 10 centimeters), with pleat tips along an upstream end provide an inlet face for the deep pleat filter and wherein pleat tips along a downstream end provide an outlet face for the deep pleat filter. The deep pleat pack is sealingly connected to each of the four sides of the rectangular border frame to prevent unfiltered bypass therebetween.

[0031] According to the above, the multilayered filter media may be formed with a plurality of embossments maintaining rigidity and spacing between a plurality of pleat panels within each pleat pack, and optionally adhesive beads connecting between embossments and pleat panels.

[0032] As an alternative to a deep pleat, a V-bank filter may be provided comprising multilayered filter media. The V-bank filter comprises: a rectangular header frame; a plurality of pleat packs, each pleat pack formed from a rectangular pleated filter element of the multi-layered filter media with at least one adjacent pair of the pleat packs being arranged in a V-configuration extending between an inlet end at the rectangular header frame and an outlet end spaced therefrom, the members of each adjacent pair of the pleat packs being connected and diverging away from each other as the members extend away from one of the inlet end and the outlet end, thereby to provide the V-configuration; and a pair of side panels extending from opposite sides of the rectangular header frame toward the outlet end and covering open sides between the adjacent pairs of pleat packs to prevent unfiltered bypass.

[0033] Other aspects are directed toward methods of forming a multi-layered filter media. A preferred method for forming multi-layered filter media comprises: providing a first filter media composite having a first nanofiber layer deposited upon a first

bicomponent support layer; providing a second filter media composite having a second nanofiber layer deposited upon a second bicomponent support layer; and thermally laminating the first and second filter media composites together with the first and second nanofiber layers abutting each other to create a laminated media, with each of the first and second bicomponent support layers including a plurality of fibers including a high melt component and a low melt component to provide for bonding via the thermal laminating.

[0034] According to the method, the thermally laminating can comprise heating the first and second filter media composites to at least partially melt the low melt component and (a) bond the first and second filter media composites together and (b) bond nanofibers of the first and second nanofiber layers to the first and second bicomponent support layers.

[0035] The method may involve depositing and solvent-dissolution bonding of the first and second nanofiber layers upon the first and second multicomponent support layers, respectively, prior to thermally laminating.

[0036] Preferably, the first and second filter media composites used in such method may be identical filter media composite layers that as thermally laminated can provide a symmetrical structure through a media thickness over a central extension of the multi layered filter media.

[0037] For the method, the thermal laminating processing may more specifically comprise: heating the first filter media composite and the second filter media composite to at least of a melting point or a glass transition point of the low melt component; and pressing the first filter media composite and the first filter media composite together to thermally bond the first filter media composite and the second filter media composite together and to embed nanofibers of the first nanofiber layer and the second nanofiber layer into the low melt component.

[0038] The method may further comprise: after the thermal laminating, embossing the first and second filter media composites by: (a) heating the laminated media; and (b) pressing spacer embossments into the laminated media to create a plurality of embossments.

[0039] Preferably, the pressing and creasing are conducted simultaneously with a pair of embossing rolls having embossing projections and score extensions.

[0040] Preferably, the method includes bonding with an adhesive bead at least some of spacer embossments of adjacent pleat panels.

[0041] Preferably, the method may also comprise creasing the laminated media and pleating the laminated media among the pleats to create a pleat pack.

[0042] Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:

[0044] FIG. 1 is a partly schematic cross section of two bicomponent support layers each having a nanofiber layer thereon (providing an intermediate filter media composite), which are thermally laminated into a multi-layer filter media composite with the nanofiber layers sandwiched between the bicomponent support layers, in accordance with an embodiment of the present invention. [0045] FIG. 2 is a schematic side view of force spinning machine assembly, which provides force-spun application of a nanofiber layer to bicomponent support layer that can be used to create the intermediate filter media composites shown in FIG. 1.

[0046] FIG. 3 is a schematic side view of a thermal lamination machine assembly for thermally laminating two of the intermediate filter media composites together, to complete the thermal lamination and achieve the multi-layer filter media composite of FIG. 1; and

[0047] FIG. 4 is schematic side view of a media scoring, embossing and pleat stacking machine assembly using the multi-layer filter media composite of FIG. 1 and created in FIG. 3 to create an embossed pleat pack.

[0048] FIG. 5 is a SEM photograph of a coarse sheath/core type bicomponent fiber of the type of fibers used in the bicomponent support layers of FIG. 1.

[0049] FIG. 6 is a SEM photograph of a nanofiber layer applied on a bicomponent support layer such as for the media of FIG. 1.

[0050] FIG. 7 is SEM photograph of the media shown in FIG. 6, but with higher magnification to show thermal melt bonding of nanofibers to coarse bicomponent fiber.

[0051] FIG. 8 is SEM photograph of the media shown in FIG. 7, but with even higher magnification to show even closer detail of the thermal melt bonding of nanofibers to coarse bicomponent fiber.

[0052] FIG. 9A is an isometric view of a V-bank filter employing the multi-layer filter media composite of FIG. 1 and pleat packs that can be accomplished according to processing of FIG. 4.

[0053] FIG. 9B is an isometric view of a deep pleat filter employing the multi-layer filter media composite of FIG. 1 and pleat packs that can be accomplished according to the processing of FIG. 4. [0054] FIG. 10 is an embossed and adhesively bonded rectangular pleat pack such as shown in FIG. 9B (or alternatively for the pleat pack of FIG. 9A, the difference being that the pleats of the pack used for the filter of FIG. 9B are much deeper than those used for the filter of FIG. 9A), which uses the multi-layer filter media composite of FIG. 1.

[0055] FIG. 11, is a partly schematic cross section of the pleated filter media of the pleat pack of FIG. 10 (embossments not shown).

[0056] FIG. 12 is an enlarged schematic plan view through two pleats of the pleat pack shown in FIG. 10 taken from one of the flow faces (in this case designated as inlet face).

[0057] FIG. 13 is a close-up perspective view of the pleat pack shown in FIG. 10 to better illustrate embossments and adhesive bead attachments that is similar to that of FIG.

12 but in perspective view and taken from the outlet face (that due to symmety appears the same as the inlet face such that this is also representative of the inlet face).

[0058] FIG. 14 is a perspective view of an embossed and scored section of the multi layer filter media composite of FIG. 1 and processed according to the machine of FIG. 4, prior to adhesive application and pleat stacking for use in creating the pleat pack of FIG. 10.

[0059] FIG. 15 is graph of a filter media composite using a multi-layer filter media composite similar to that of FIG. 1, except that the media is ultrasonically point bonded rather than thermally laminated, showing air permeability (AP) and filtration efficiency (Effici) comparisons before and after embossing.

[0060] FIG. 16 is graph of a filter media composite using a multi-layer filter media composite of FIG. 1 that is thermally bonded using bicomponent bonding (rather than ultrasonic bonding) and also showing air permeability (AP) and filtration efficiency (Effici) comparisons before and after embossing.

[0061] While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

[0062] Turning to FIG. 1, an embodiment of the present invention is shown as a multi layer filter media composite 10 constructed from two separate intermediate filter media composites 12 that are bonded together, preferably by thermal lamination.

[0063] Each intermediate filter media composite 12 comprises a bicomponent support layer 14 with a nanofiber layer 16 deposited thereon.

[0064] The bicomponent support can provide for nanofiber protection, a nanofiber coating carrier, stiffness for pleating and elasticity for embossing.

[0065] With additional reference to FIG. 5 (see also FIGS. 6 and 7) each bicomponent support layer 14 includes a plurality of coarse fibers 18, which includes a high melt component 20 and a low melt component 22. The high melt component has a high melting point than the low melt component. The coarse fibers 18 may be spunbond or can be provided by other fiber generation methods. The low melt component 22 facilitates bonding, preferably for example, by thermal lamination.

[0066] With the low melt component, the intermediate filter media composites 12 are thermally laminated together with the nanofiber layers 16 sandwiched between the bicomponent support layers 14 as shown in FIG. 1. With thermal lamination and this configuration of the thermally laminated multi-layer filter media composite 10 (for example, which may be completed by the process of FIG. 3), the nanofiber layers 16 are bonded to the first and second bicomponent support layers 14 via the low melt component 22. Also, the low melt component 22 bonds the first and second bicomponent support layers 14 together by having melt bonded points between the coarse fibers 18 of each intermediate filter media composites 12. In this manner, the top intermediate filter media composite 12A is bonded to the bottom intermediate filter media composite 12B through low melt component bonding of the coarse fibers of the top intermediate filter media composite 12A directly with coarse fibers of the bottom intermediate filter media composite 12B, in addition to fixing and support the nanofibers 24 of the nanofibers layers 16 with the coarse fibers.

[0067] Preferably, the first intermediate filter media composite 12A and the second intermediate filter media composite 12B are of a same construction. For example, each of the first media composites 12A, 12B may comprise the same caliper thickness, fibers types, fiber sizes and/or basis weights of coarse fibers and nanofibers. For example, each of the first media composites 12 A, 12B may be made from the same process shown in FIG. 2, with the same bicomponent support layer 14 having deposited thereon a nanofiber layer 16.

[0068] By using the same filter media composite for each of first intermediate filter media composite 12A and the second intermediate filter media composite 12B, this can provide a symmetrical structure through a media thickness over a central extension (e.g. the central horizontal lamination plane of multi-layer filter media composite 10 shown FIG. 1). This provides more consistent processing characteristics such as when embossments may be struck to project from both top and bottom surfaces as well as providing nanofiber fixation and protection from both sides. The use of two support layers (such as provided by spunbond scrims) that are bonded during thermal lamination protect the nanofiber layer and achieve enough stiffness for embossing and pleating processing.

[0069] The bicomponent coarse fibers 18 may be of a core and sheath configuration shown in FIG. 5 with the high melt component internal to the low melt component, although other bicomponent configurations can be used including a side-by-side, a segmented, an islands-in-the-sea, or other arrangement.

[0070] A preferred embodiment may utilize coarse fibers 18 that include a high melt polyester and a low melt polyester, although other embodiments may use polymers from different families. For example, the coarse fibers 18 can comprise at least one polymer type selected from the group consisting of: a polyester, a PEN polyester, a PCT polyester, a PBT polyester, a soluble co-polyester, a polyamide, a polystyrene, a co-polyamide, a polylactic acid, an acetal, a polyurethane, a polystyrene, a high-density polyethylene, and a linear low density polyethylene. [0071] As used herein bicomponent comprises at least two or more component materials (usually only two component materials but in some embodiments more than two) having at least slightly different physical properties. As an example typically used in embodiments herein, a bicomponent includes a single fiber and/or multiple fibers in a layer that includes a high melt component and a low melt component in which the high melt component has a higher melting point than the low melt component. The components can be from the same or entirely different polymer types, and each might possess distinct physical or chemical properties.

[0072] The bicomponent support layers 14 preferably comprise scrims. Each individual scrim may have a basis weight preferably between 10 gsm and 200 gsm (more preferably between 10 and 100 gsm, and most preferably about 40 gsm). As used herein, by“gsm” it is meant herein grams per square meter; and“about” it is meant to encompass a variance of up to 20% from the stated value. Each individual scrim may also have coarse fibers with an average fiber size preferably between 2 micron and 30 micron (more preferably between 5 micron and 25 micron, and most preferably between 10 micron and 20 micron); and a caliper thickness preferably between 0.03 millimeter and 0.75 millimeter (more preferably between 0.1 and 0.5 millimeter and most preferably about 0.25 millimeter).

[0073] The nanofiber layers 16 typically are very thin due to the very fine size of the nanofiber 24 such that FIG. 1 is schematic and not to scale. Layer thickness of the nanofiber layers 16 are multiple times thinner than the support layers 14. For example, FIGS. 6-8 illustrate nanofibers thermally melt bonded to the coarse fibers after thermal lamination. Separate formation of nanofiber layers 16 include a top nanofiber layer 16A on a top bicomponent support layer 14A and a bottom nanofiber layer 16B on a bottom bicomponent support layer 16B. “Top” and“bottom” simply being used herein relative to the orientation shown in FIG. 1 and 3, understanding that if the media is upside down the top becomes the bottom and vice versa.

[0074] Each nanofiber layer 16 is made of nanofibers, and for example may comprise: a basis weight preferably between 0.005 gsm and 1.5 gsm (more preferably between 0.05 and 0.6 gsm and most preferably about 0.4 gsm); and an average fiber size of such nanofibers of preferably no greater than 250 nanometer (more preferably between 50 nanometer and 150 nanometer and most preferably between 80 nanometer and 100 nanometer); and a caliper thickness for the layer of preferably between .005 and 0.1 millimeter (more preferably about .03 millimeter).

[0075] The nanofiber layers comprise nanofibers comprising at least one polymer type selected from the group consisting of: a polyamide, a polyvinylidene fluoride, a

polytetrafluoroethylene, a polyurethane, a cellulose acetate, a polycarbonate, and a polystyrene. For example, nylon 6 (i.e. polyamide 6) or other such nylons (e.g. nylon 66 or other polyamides) are preferred.

[0076] The nanofibers 24 and nanofiber layers 16A, 16B are preferably produced by force-spinning methods that employ high speed centrifugal forces to transform material into fibers such as discussed in US Patent 10,240,257 to Kay et. al entitled“Systems and methods for controlled laydown of materials in a fiber production system”, which is incorporated by reference. Other publications regarding creating fibers using centrifugal forces (i.e. force-spinning) may be found in the following U.S. Patent Application

Publication Nos: 2009/0280325 entitled“Methods and Apparatuses for Making Superfine Fibers” to Lozano et al; 2009/0280207 entitled“Superfine Fiber Creating Spinneret and Uses Thereof’ to Lozano et al.; 2014/0042651 entitled“Systems and Methods of Heating a Fiber Producing Device” to Kay et al; 20140159262 entitled“Devices and Methods for the Production of Microfibers and Nanofibers in a Controlled Environment” to Kay et al.

2014/0035179 entitled“Devices and Methods for the Production of Microfibers and Nanofibers” and U.S. Pat. No. 8,721,319 entitled“Superfine Fiber Creating Spinneret and Uses Thereof’ to Lozano et al.; U.S. Pat. No. 8,231,378 entitled“Superfine Fiber Creating Spinneret and Uses Thereof’ to Lozano et al.; U.S. Pat. No. 8,647,540 entitled“Apparatuses Having Outlet Elements and Methods for the Production of Microfibers and Nanofibers” to Peno; U.S. Pat. No. 8,777,599 entitled“Multilayer Apparatuses and Methods for the Production of Microfibers and Nanofibers” to Peno et al.; U.S. Pat. No. 8,658,067 entitled “Apparatuses and Methods for the Deposition of Microfibers and Nanofibers on a

Substrate” to Peno et al.; U.S. Pat. No. 8,647,541 entitled“Apparatuses and Methods for Simultaneous Production of Microfibers and Nanofibers” to Peno et al; U.S. Pat. No.

8,778,240 entitled“Split Fiber Producing Devices and Methods for the Production of Microfibers and Nanofibers” to Peno et al; and U.S. Pat. No. 8,709,309 entitled“Devices and Methods for the Production of Coaxial Microfibers and Nanofibers” to Peno et al; all of which are incorporated herein by reference.

[0077] In alternative embodiments, electrospinning or other fine fiber generation may be used to create the nanofibers 24 and nanofiber layers 16A, 16B, with such

electrospinning or other fine fiber generation discussed by various patents in the background section above.

[0078] An example formulation of a multi-layer filter media composite 10 is detailed in TABLE 1 below (layers corresponding to reference numbers in drawings such as FIG. 1), also illustrating symmetrical construction.

[0079] TABLE 1 - Example Construction Of Multi-layer Filter Media Composite

*Ranges in parenthesis indicating variance from preferred parameter.

[0080] With such configurations, a suitable media for efficiency and air permeability can be provided. For example, the multi-layered filter media according to the above construction comprises has a pressure drop less than 0.4 inch of water at 1968 cfm air flow measured according to ASHRAE 52.2, and an isopropyl alcohol discharged efficiency MERV rating of at least 14 measured according to ASHRAE 52.2.

[0081] Turning to FIGS. 2-3, a method of forming the multi-layered filter media composite 10 is schematically illustrated. Referring first to FIG. 2, the intermediate filter media composite 12 is first produced for use of top and bottom intermediate filter media composites 12A, 12B. As shown, a scrim roll 26 feeds a continuous sheet of the bicomponent support layer 14, through a centrifugal force-spinning machine assembly 28 contained within a fume collection enclosure 29 that can collect evaporated solvent. The force-spinning station 28 includes one or more (or a series of) spinning emitters 30 that rotates at high speeds and is fed with at least partially dissolved and/or melted polymer material to generate nanofibers 24 that are deposited upon the bicomponent support layer 14 and thereby the nanofiber layer 16 thereon, as schematically indicated. The produced intermediate composite 12 may then be gathered on a rewound, intermediate composite roll 32 (of the intermediate composite 12) for later use to provide for either or both of the intermediate filter media composites 12 A, 12B used to create the multi-layer filter media composite 10.

[0082] In the process of FIG. 2, preferably the nanofibers 24 are produced from a polymer solution in which the solvent is mostly evaporated during expelling and attenuation of fibers before being deposited upon the bicomponent support layer 12, although polymer melt or heat assisted polymer solution may be employed. Residual solvent on the nanofibers when deposited creates a weak but sufficient bond for later processing. In particular, the residual solvent leaves the nanofiber with sticky surface while it’s not completely transferred from polymer solution to dry polymer nanofiber upon solvent drying, and that residual solvent facilitates“solvent-dissolution bonding” to the

bicomponent support layer 12 sufficient for later processing (e.g. rewinding and/or thermal lamination of FIG. 3).

[0083] Turning to FIG. 3, FIG. 3 schematically illustrates a thermal lamination machine assembly to generate the multi-layer filter media composite 10. The process starts with a pair of the intermediate composite rolls 32 that may be produced according to the method of FIG. 2. The top and bottom intermediate filter media composites 12A, 12B sheets are fed from the rolls 32 on a continuous process through a thermal lamination oven 34 which preferably has therein laminating pinch rolls 36 that have a gap slightly less than the total caliper thickness of the combination of the two top and bottom intermediate filter media composites 12A, 12B sheets. This thermally laminates the top and bottom intermediate filter media composites 12 A, 12B together with the first and second nanofiber layers abutting each other and sandwiched between the scrim layers to create the multi-layer filter media composite 10 as shown in FIG. 1. As noted above, each of the bicomponent support layers 12 (including a plurality of coarse fibers including a high melt component and a low melt component) provide for bonding preferably via the thermal laminating. The completed multi-layer filter media composite 10 may then be collected on a completed filter media roll 38 to be stored or if ready it may be transferred for further processing.

[0084] During the process, the oven 34 is set at a temperature and time that heats the intermediate filter media composites 12 A, 12B to at least partially melt the low melt component sufficiently to facilitating (a) bonding of the intermediate filter media composites together; and also (b) bonding of nanofibers of the nanofiber layers to the bicomponent support layers. In particular, the process heats the intermedia filter media composites to at least of a melting point or a glass transition point of the low melt component 20. This achieves melt bonding of the layers together along with bonding of nanofibers thereto. For example, nanofiber bonding via thermal lamination is shown in FIGS. 6-8.

[0085] Preferably the thermally laminating comprises heating both of the intermediate filter media composites 12A and 12B and also further pressing those together via the pinch rolls 36 to better ensure attachment, more complete lamination and melt bonding.

[0086] While other uses exist, one advantageous application is in embossed and pleated filter medias such as may be produced according to FIG. 5, and to generate pleat packs as in FIGS. 10-14 that in turn can be used in filters such as shown in FIGS. 9 A, 9B.

[0087] For example, a media scoring, embossing and pleat stacking machine assembly 40 shown in FIG. 5 embosses and pleats of the multi-layer filter media composite 10. The machine assembly 40 starts with a completed filter media roll 38 from which a sheet of the multi-layer filter media composite 10 is advanced. The advanced sheet of multi-layer filter media composite 10 feeds through scoring and embossing rolls 42. With additional reference to FIGS. 12-14, these rolls 42 create both embossments (which may include adhesive spacer bead embossments 44 and pleat support embossments) as well as score lines 48. The scoring and embossing rolls 42 include embossing projections and score extensions (only schematically represented in FIG. 4) that when contacting the media apply pressure to plastically deform the multi-layer filter media composite 10. To assist in plastic deformation, heat is applied via an oven 43 prior to the rolls and/or heat applied to the rolls 42 to soften the media.

[0088] Another novel aspect is using bicomponent type media to such an embossed, pleated media construction.

[0089] Examples of embossing methods of embossed filter medias are described in U.S. Pat. No. 6,685,833; U.S. Pat. No. 5,290,447; U.S. Pat. No. 5,804,014; and DE 19755466, any of which may be applied to the multi-layer filter media composite 10 as an addition or alternative according to embodiments. Each of these patents are incorporated by reference in their entireties, as these or other pleating and embossing technologies may be used.

[0090] After passing through scoring and embossing rolls 42 the multi-layer filter media composite 10 is plastically deformed and appears with embossments 44, 46 and score lines 48 as shown in FIG. 14. Referring again to FIG. 4, intermittent application of adhesive beads 50 via adhesive applicators 52 to top and bottom sides of the multi-layer filter media composite 10 is conducted over the adhesive spacer bead embossments 44 at the regions of the score lines 48, and the multi-layer filter media composite 10 is processed through a pleat stacker 54 that folds the composite into pleats 56 that have pleat panels 58 that extend between pleat tips 60 along an outlet face 62 and pleat tips 60 along an inlet face 64. The pleat panels 58 thereby provide multiple sections of the multi-layered filter media composite 10 that extend between the inlet face and the outlet face as shown in FIG. 11.

[0091] The pleated media can then be cut to create rectangular pleat packs 66 such as shown in FIG. 10, with the score lines 48 forming pleat tips 60. Adhesive bead support embossments 44 can arranged for contact and adhesive attachment via the adhesive beads 50 as shown in FIG. 13.

[0092] In the completed pleat pack 66, the filter media is folded into multiple pleats 16 to provide sets of pleat tips 60 on each side (both inlet and outlet sides) facilitated by the score lines 48. Pleats 58 are provided with the full face of pleat panels 58 exposed during use (not blinded) with structural support such as provided by embossments 44, 46 and adhesive beads 50, with a pleat density preferably between 1.5 and 4.5 pleats per inch. As for size, for typical applications, the pleat pack 66 (and resulting panel filters) may span a first lateral span of between 6 and 30 inches and a second lateral span transverse to the first span that is also between about 6 and 30 inches.

[0093] Pleat depth can be measured normal to these spans. In various embodiments, the pleat depth may be between 1 and 12 inches (fractions being rounded up in this instance considering that the panel filter element need only fit an envelope that size; thus a %th inch pleat depth would be considered a 1 inch depth filter). For many embodiments with a plastic frame for many industrial applications, the pleat depth between 4 inches and 12 inches, with perpendicular lateral spans between 12 inches and 30 inches to form a square or other rectangular pack shape.

[0094] To achieve an organized filter media configuration and support for the multi layer filter media construction 10, the pleat pack 66 employs the adhesive beads 50 which can serve as spacers in conjunction with the embossments. Adhesive beads 50 may be continuous or more preferably discontinuous, and which are laid down by the adhesive bead applicators 52 (see FIG. 4) applied during manufacture upon both the inlet side for forming inlet face 64 and outlet side for forming outlet face 62. The beads 50, serve to provide structural support to the pleated filter media to hold the structure into a rectangular filter media pleat pack 66.

[0095] Generally, the adhesive beads 50 are continuous or discontinuous strips of adhesive that are laid as the media is being run in the direction of the second span in a continuous manner over each of the inlet face 64 and outlet face 62 to form the bead spacer structures on opposing sides of the filter media. As can be seen in FIGS. 11-13, the adhesive beads 50 therefore extend up and over pleat tips 60 and down partially into pleat valleys along the pleat panels 58 and therefore at least partially into the V-shaped channels 61 formed between adjacent pleat panels 58.

[0096] The V-shaped channels 61 depending upon which way they are facing provide inlet pleat channels facing the inlet face and outlet pleat channels facing the outlet face. The embossments 44, 46 formed into the multi-layered filter media project into the inlet pleat channels and into the outlet pleat channels provided by V-shaped channels 61 to narrow the gaps proximate the pleat tips to provide for adhesive attachment. Therefore, FIG. 13 can be representative of both the inlet face and the outlet face due to symmetry (e.g. the pleat pack when viewed from the inlet side or the outlet side appears the same) to show how embossments project into either the inlet channels or outlet channels provided by V-shaped channels 61.

[0097] Alternatively, in some embodiments the adhesive beads 50 may reach all the way to the bottom of such V-shaped channels as the adhesive spacer beads are laid continuously.

[0098] The adhesive beads 50 may be laid down in parallel lines at a spacing (relative to the next adjacent adhesive bead) between ½ and 4 inches and in some embodiments, more preferably between 1 and 2 inches. This provides sufficient structural support to maintain the pleat shape and V-shaped channels 61 with sufficient open volume to provide airflow without undue restriction. The adhesive beads 50 also afford support to prevent the pleats from collapsing and contacting each other to prevent blinding off the filter media during operation.

[0099] For example, V-shaped channels 61 do not deform or collapse very much during use, which maintains airflow into the channels to move through filter media of pleat panels 58. As a result, much more of the surface area of the pleated multi-layer filter media composite 10 is exposed for full filtration and dust loading purposes. Further, the configuration allows for dust cake accumulation without prematurely filling or blocking the V-shaped channels 61 with this pleat density and support structure configuration. [0100] To assist in the spacing and structural integrity, various embossments 44, 46 are preferably provided to widen the pleat panels 58 at select areas where the adhesive beads 50 are laid down. This can be done, for example, in FIG. 4 whereby adhesive support embossments 44 are formed such as by heat setting and/or compression forming into the pleat flanks panels 58 every 1 to 2 inches (or between ½ and four inches in some other embodiments depending upon the spacing of the adhesive spacer beads 36). Adhesive support embossments 44 provided a shorter span needed for the adhesive to bridge across the V-shaped channels 61 between adjacent pleat panels 58.

[0101] Additionally, additional support embossments 46 may be interspaced between the adhesive bead support embossments 44 as illustrated also at a similar spacing of the adhesive bead support embossments 44. These other embossments 46 do not receive a glue bead, but provide for additional structural support and also help prevent flat surface-to- surface contact between filter media along the pleat panels 58 in response to airflow forces during use.

[0102] Referring to FIG. 10, it can be seen that this construction can provide a filter media pleat pack 66 that has employed the adhesive beads 50 and embossments 44, 46 (shown in FIGS. 12-14) such that the filter media pack 22 is ready to be framed for use in one of the embodiments of FIGS. 9A and 9B.

[0103] If used in the deep pleat configuration of FIG. 9B, the pleat depth will typically be at least 4 inches, whereas if in the embodiment of multiple pleat panels arranged in a V- Bank configuration of FIG. 9A, then pleat depth will typically be less than 4 inches, and in such an embodiment, embossments and/or adhesive beads may not be as necessary and/or may simple not be used (i.e. the multi-layer filter media composite 10 may be simply pleated into a pleat pack without embossments or adhesive spacers).

[0104] FIGS. 9B illustrates an embodiment of a deep pleat panel filter 70 utilizing the embossed sheet of FIG. 14 according to the embossing process of FIG 4 that creates the pleat pack 66 used in the panel filter 70. The panel filter 70 secures the pleat pack 66 in this embodiment by a suitable support structure such as a rectangular plastic border frame 72 that has a rectangular header flange 74 to which a rectangular gasket can be applied. The border frame 72 can be a single component or multiple assembled component parts. The pleat pack 66 is sealingly connected to each of the four sides of the rectangular border frame to prevent unfiltered bypass therebetween. By sealingly connected it is meant that adhesive sealant is applied, or a flange of a pleat panel is trapped or pinched to prevent unfiltered bypass, or other sealing connection is provided with or without adhesive or sealant. The header flange 74 can be used for mounting and sealing in an animal confinement building application such as shown in various patents assigned to Clarcor Air Filtration Products,

Inc. such as U.S. Patent Nos. 9,510,557; 9,126,135; 8,747,505; and 10,507,416, which are all incorporated by reference in their entireties.

[0105] As an alternative to a deep pleat panel filter 70 and also apparent from the aforementioned patents in the previous paragraph, multiple pleat packs 66 of the multi layered filter media may be configured into a V-bank filter 80 configuration as shown in FIG. 9A, which also may be used in animal confinement buildings. In this embodiment, a rectangular header frame 82 is provided that supports at least one adjacent pair 84 of the pleat packs 66 being arranged in a V-configuration extending between an inlet end 86 at the rectangular header frame 82 and an outlet end 88 spaced therefrom (preferably by at least 6 inches), with the members of each adjacent pair of the pleat packs being connected such as by bridge channels 90 and diverging away from each other as the members extend away from one of the inlet end and the outlet end, thereby to provide the V-configuration with open V-shaped receiving gaps 92 (that are different and much larger than the pleat valleys 61). Side panels 94 extend from opposite sides of the rectangular header frame 82 toward the outlet end 88 and covering open sides between the adjacent pairs 84 of pleat packs 66 to prevent unfiltered bypass.

[0106] While animal confinement applications are a significant application for the multi-layer filter media composite 10, the multi-layer filter media composite 10 may also be used in other air filtration applications such as HVAC, Engine air, facemasks, and cabin air filters.

[0107] Turning to FIGS. 15 and 16, it is shown that thermal lamination helps to protect nanofibers with the low melt affixation during the embossing/pleating process. In each of these, a multi-layer filter media composite having two scrims and two nanofiber layers (e.g. such as described above with reference to FIG. 1) was utilized with each being subjected to emboss and pleat processing such as schematically illustrated and described in FIG. 4. The difference being that the FIG. 15 example used a multi-layer filter media composite that was ultrasonically pointed bonded (not thermally laminated as in FIG. 3 process), while FIG. 16 example used a multi-layer filter media composite that was thermally laminated (e.g. such as by the FIG. 3 process). In each example, the media air permeability and filtration efficiency was tested after bonding and then again after emboss processing. As apparent, the thermal lamination maintains and matches the media air permeability and filtration efficiency, such that the embossing and pleat processing had little or no effect as shown in FIG. 16. In contrast, ultrasonic bonding caused changes in both filtration efficiency (drop by 10%) and air permeability (increasing by about 25%) due to emboss and pleat processing.

[0108] All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0109] The use of the terms“a” and“an” and“the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms“comprising,”“having,”“including,” and “containing” are to be construed as open-ended terms (i.e., meaning“including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g.,“such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non- claimed element as essential to the practice of the invention. [0110] Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.